Recently, a fingerprint identification module has gradually become an essential component of an electronic device. The fingerprint identification module is used to recognize the identity of the user. Consequently, the user can unlock the electronic device or operates an application program through the fingerprint identification module.
Generally, the fingerprint identification module detects the fingerprint according to a capacitive fingerprint sensing technology or an optical fingerprint sensing technology. The optical fingerprint sensing technology was developed earlier. In accordance with the optical fingerprint sensing technology, an optical fingerprint sensing unit captures the light beam that is reflected from the surface of the finger, and compares the brightness/darkness difference between the fingerprint crests and the fingerprint troughs to obtain the texture details of the fingerprint of the finger. In comparison with the capacitive sensing chip of the capacitive fingerprint sensing unit, the optical fingerprint sensing chip of the optical fingerprint sensing unit is more cost-effective and more durable.
Conventionally, in case that the portable electronic device uses the capacitive fingerprint sensing technology, the capacitive sensing unit is disposed under a physical key. In case that the portable electronic device uses the optical fingerprint sensing technology, the surface of the portable electronic device is equipped with a transparent window or an opening, and the optical fingerprint sensing unit is located under the transparent window or embedded in the opening. The transparent window or the opening is used for recognizing the fingerprint only. That is, the transparent window or the opening does not provide any other function. However, the uniform and aesthetically-pleasing appearance of the portable electronic device is possibly influenced by the transparent window or the opening. If the transparent window or the opening is not completely sealed, moisture or dust possibly enters the portable electronic device through the junction between the transparent window and the portable electronic device or through the opening. Under this circumstance, the optical fingerprint sensing unit or other electronic components may be suffered from a short-circuited problem or even the portable electronic device may be suffered from breakage or damage.
For solving the drawbacks of the conventional technology, there is a need of providing a portable electronic device with a novel structure for preventing moisture or dust from entering the portable electronic device through the location of the optical fingerprint sensing unit. Moreover, the uniform and aesthetically-pleasing appearance of the portable electronic device is not adversely affected by the novel structure of the portable electronic device.